Method and Apparatus for Preamble Training with Shortened Long Training Field in a Multiple Antenna Communication System

1. A method for receiving a preamble on at least one receive antenna transmitted by a transmitter having N transmit antennas in a multiple antenna communication system, said method comprising the steps of: receiving, on said at least one receive antenna, a first part of said a preamble, said first part having at least one long training field: and receiving, on said at least one receive antenna, a second part of said preamble, said second part having and an extended portion having at least N additional long training fields, wherein one of said at least N additional long training fields is comprised of two OFDM symbols, wherein N−1 of said at least N additional long training fields consist of only one OFDM symbol and wherein N is an integer greater than one.

2. The method of claim 1 , wherein said preamble is a legacy preamble.

3. The method of claim 1 , wherein only said N additional long training fields are used for MIMO channel estimation.

4. The method of claim 1 , wherein said extended portion further includes one or more of a short training field for power estimation and a signal field identifying a preamble format.

5. The method of claim 1 , wherein said extended portion further comprises one or more additional OFDM symbols for frequency offset estimation.

6. The method of claim 1 , wherein said extended portion comprises a first high throughput long training field comprised of two repeated OFDM symbols and N−1 high throughput long training fields comprised of only one OFDM symbol.

7. The method of claim 1 , wherein said extended portion comprises N high throughput long training fields comprised of only one OFDM symbol.

8. A receiver in a multiple antenna communication system having at least one transmitter having N transmit antennas, comprising: a receiver circuit; and at least one receive antenna for receiving a preamble having at least one long training field and an extended portion having at least N additional long training fields, wherein one of said at least N additional long training fields is comprised of two OFDM symbols, wherein N−1 of said at least N additional long training fields consist of only one OFDM symbol and wherein N is an integer greater than one.

9. The receiver of claim 8 , wherein said preamble is a legacy preamble.

10. The receiver of claim 8 , wherein only said N additional long training fields are used for MIMO channel estimation.

11. The receiver of claim 8 , wherein said extended portion further includes one or more of a short training field for power estimation and a signal field identifying a preamble format.

12. The receiver of claim 8 , wherein said extended portion further comprises one or more additional OFDM symbols for frequency offset estimation.

13. The receiver of claim 8 , wherein said extended portion comprises a first high throughput long training field comprised of two repeated OFDM symbols and N−1 high throughput long training fields comprised of only one OFDM symbol.

14. The receiver of claim 8 , wherein said extended portion comprises N high throughput long training fields comprised of only one OFDM symbol.